Transformation of Oligomeric Ellagitannins, Typical for Rubus and Fragaria Genus, during Strong Acid Hydrolysis

Abstract

The strong acid hydrolysis analysis of galloyl- O -digalloyl-type ellagitannins (ETs), lambertianin C (LC) and sanguiin H-6, and dehydrodigalloyl-type ET, agrimoniin (AM), was performed. A quantitative and qualitative analysis of the degradation products of individual ETs was conducted using high-performance liquid chromatography–diode array detecto–electrospray ionization interface–mass spectrometry (HPLC–DAD–ESI–MS). The data indicate that ETs undergo multidirectional changes in a strongly acidic environment, where the process of successive hydrolysis of ester bonds to form ellagic acid (EA) is the dominant phenomenon in the initial phase of the reaction, followed by the depolymerization process and the formation of low-molecular ETs. Characteristic products of ET hydrolysis were distinguished: for LC: dimeric ET plus one galloyl moiety without one EA moiety ( M = 1736 Da), for all analyzed ETs: sanguisorbic acid dilactone ( M = 470 Da), and for AM: dehydrodigallic acid ( M = 338 Da). The research carried out has allowed to create a database of possible products and routes of transformation of individual ETs, which should facilitate future research on the transformation of ETs, including potential prohealth properties of its breakdown products, under conditions occurring during food processing or digestion.

Variation of the Polyphenolic Composition and Antioxidant Capacity of Freshly Prepared Pomegranate Leaf Infusions over One-Day Storage

“…Apart from phenolic profiling, an outline regarding the hypothetical synergistic or antagonistic transformation of identified polyphenolics of PLI during one-day storage was roughly envisaged for the first time ( Figure 2 ). In keeping with the literature references [ 6 , 7 , 22 , 23 , 27 , 30 , 31 , 32 , 33 , 41 , 42 , 43 , 44 ], this transformation effect of these polyphenolic compounds might involve their hydrolysis, polymerization, antioxidative cleavage, and conformational changes, among others, presumably linking to environmental factors, such as temperature, oxygen, pH, and light.…”

“…(i) Part of EAD degraded to ellagic acid by hydrolysis [ 30 ], leading to a decrease during storage.…”

“…However, ET-III and ET-VI presented the lowest amounts at 0 h and higher deterioration at 24 h. The stability of ET-III, ET-IV, ET-VI, and ET-VIII was more perceptible in the first 4 h and secondly stable at 6–8 h. Except for other degraded phenolics, the peak of ET-VII was found at 6 h storage and not at 0 h, which was speculated as HHDP-glucosides, the intermediate molecular weight fragments. The concentration of ET-VII increased from the partial breakdown of polyphenols (high-molecular weight ETs) before 6 h and then decreased by subsequent chain destruction into low-molecular compounds, such as ellagic acid [ 30 , 31 , 32 ].…”

“…Elucidating the native structural variations of ETs was often a challenge, yet, according to other relevant reports [ 16 , 27 , 28 , 30 , 33 , 34 ], ET-I, -II, -V, and -IX can be assumed as ellagitannin monomers or HHDP intermediates, of which the ascending concentrations were likely attributed to the decomposition of some uncertainly identified ellagitannin oligomers or monomers or to the intricate transformation of other ETs or gallotannins.…”

Water-Soluble Melanoidin Pigment as a New Antioxidant Component of Fermented Willowherb Leaves (Epilobium angustifolium)

“…This means that fermentation of E. angustifolium leaves affected mainly the ellagitannins and derivatives of gallic and ellagic acids; moreover, the breakdown of ellagitannins led to the release of free gallic and/or ellagic acids. Similar processes have been previously described for the hydrolytic cleavage [ 59 , 60 ] and microbial transformation of ellagitannins [ 40 , 61 ].…”